Some fuel injection systems for automotive engines have a plurality of fuel injectors each of which delivers fuel to the inlet port of an associated engine combustion chamber. In some such systems, the fuel injectors are mounted in sockets of a fuel rail which has a passage to supply fuel to the injectors; the fuel rail simplifies installation of the fuel injectors and the fuel supply passage on the engine.
When electromagnetic injectors are employed in such a system, the injectors deliver fuel to the engine in pulses which are timed to control the amount of fuel delivered. The duration of the fuel pulses is calculated to deliver the proper amount of fuel in liquid form, and the fuel system must assure that the fuel injectors receive only liquid fuel; if fuel vapor is entrained in the fuel supplied to the injectors, the fuel pulses will not contain the required amount of fuel.